A power tool includes a housing, a motor positioned within the housing, and an impulse assembly coupled to the motor to receive torque therefrom. The impulse assembly includes a cylinder at least partially forming a chamber containing a hydraulic fluid, an anvil positioned at least partially within the chamber, and a hammer positioned at least partially within the chamber. The hammer includes a first side facing the anvil and a second side opposite the first side. The impulse assembly further includes a biasing member biasing the hammer towards the anvil, and a valve movable between a first position that permits a first fluid flow rate of the hydraulic fluid in the chamber from the second side to the first side, and a second position that permits a second fluid flow rate of the hydraulic fluid in the chamber from the first side to the second side.